Regulating Incompatible Interfaces and Electron/Ion Transport in Lithium Metal Solid State Batteries

Abstract Large interfacial impedance, severe spontaneous reaction and poor ion transport efficiency between Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) and Li metal interface are the main bottlenecks restricting the development of LATP‐based solid‐state batteries. Herein, a fast Li + transfer and electron‐blocking interface composed of Li 2 O/Li x In is constructed on LATP through an in situ electrochemical reaction of In 2 O 3 with Li metal. Li 2 O with low Li + migration energy barrier and electron‐blocking injection can accelerates Li + diffusion and suppresses dendrite growth at the interface. Li x In has a high bilateral affinity with Li metal and LATP, which significantly enhances the contact between LATP and Li metal. The initial resistance of the Li/In 2 O 3 @LATP/Li symmetric battery is reduced from 1211.4 to 106.5 Ω cm −2 , and the critical current density is significantly increased to 1.9 mA cm −2 . At high current density and discharge depth, it can stably cycle without dendrites for over 3700 h at 0.2 mA cm −2 /0.2 mAh cm −2 , and 1800 h at 0.4 mA cm −2 /0.4 mAh cm −2 . The Li/In 2 O 3 @LATP/LiFePO 4 full battery shows excellent electrochemical performance, after 600 cycles, each cycle decay rate of ≈0.015% at 0.8 C and 25 °C. When matched with Li 1.2 Mn 0.6 Ni 0.2 O 2 cathode, the full battery also has good compatibility with 4.8 V and high capacity.